Monday, November 05, 2007

Years ago I heard a biologist describe an encounter they had with a spotted bat, and I remember how impressed I was by the sense of wonder and awe that I heard in that description. Perhaps it is necessary to spend one's professional life in the study of bats to get a sense of the mythical status surrounding these creatures, but I was immediately impressed with the description, and how unique and rare the spotted bat is among bats.

Spotted bats were once considered to be the rarest of North American mammals. Up until the 1990's very few had ever been collected, and most of these were dead or mummified remains. A few live spotted bats were seen, one at the entrance to a cave. However, it turns out that spotted bats are one of the few bats who's echolocation call can be easily heard by the human ear. Once this fact was discovered, biologists eventually found that, while they are still not a common species, they can be detected in many habitats where their presence was completely unknown before.

They fly high and fast in the darkest hours of the night, and they have an uncanny ability to avoid being captured using specialized techniques commonly employed by biologists who study bats. To this day, capturing one is still a rare event, and there are bat biologists who, despite years in the field, have never seen one.

I am still slightly stunned that I was along when a graduate student, working near the rim of the Grand Canyon in Arizona, caught four spotted bats over the course of two nights - even though he was trying to capture an entirely different species. This gave me a unique opportunity to get some detailed photographs of the the bat.

spotted bat (Euderma maculatum)
Below you can see the pattern of three distinctive spots that give the bat its name.

spotted bat (Euderma maculatum)spotted bat (Euderma maculatum)
A photograph cannot really show the amazing amount of character these bats have.

spotted bat (Euderma maculatum)
Bats are still largely mysterious creatures - many of their habits and roosting sites remain completely unknown. However, technology is just now giving biologists the ability to use miniature transmitters to track these tiny mammals. The female bat, seen in these images, was lactating - meaning that she had a pup hidden away somewhere. Because this capture presented a rare opportunity to track a mother spotted bat, she was outfitted with a transmitter and set free (the transmitter will fall off after a few days).

The next day a plane was chartered, and Grand Canyon National Park gave special permission to fly into the Canyon with radio telemetry gear to see if the day roost of this bat could be located. After many hours of searching, the bat's location was detected, 17 miles from the capture site the night before, in a crevice in one of the sheer cliff walls of the Grand Canyon. Presumably, she returned to nurse her young pup after a night of hunting insects in the warm Arizona night.